Water soluble polymer compositions and process for preparation thereof

ABSTRACT

THE INVENTION PROVIDES A PROCESS FOR MAKING NOVEL WATER-SOLUBLE POLYMERS WHICH ARE USEFUL AS FLOCCULATING AGENTS. THESE POLYMERS ARE FORMED BY POLYMERIZATION OF (A) ITACONIC ACID, OR THE WATER SOLUBLE SODIUM OR AMMONIUO SALTS THEREOF, IN PROPORTION OF FROM 0.2 TO 15 PERCENT BY WEIGHT; (B) A MONOMER OF AN AMIDE OF UNSATURATED ALPHA-BETA MONOCARBOXYLIC ACID, SUCH AS ACRYLAMIDE OR IMMEDIATE DERIVATIVES THEREOF, IN PROPORTION OF FROM 5 TO 95 PERCENT WEIGHT; (C) AN UNSATURATED WATERSOLUBLE MONOMER, FOR EXAMPLE: ACRYLIC ACID OR MALEIC ACID, AND THE SALTS OF SAID ACID; ALLYLALOCOHOL, AND DERIVATIVES THEREOF. THE POLYMERIZATION IS CARRIED OUT BY DISPERSING THE THREE ABOVE-DESCRIBED MONOMERS (A), (B) AND (C) IN A WATER INSOLUBLE ORGANIC MEDIUM, E.G., TOLUENE IN PRESENCE OF A SURFACE-ACTIVE AGENT SUCH AS SULPHONATED PETROLEUM DISTILLATE WITH A MOLECULAR WEIGHT IN THE RANG E OF 300 TO 1000, A POLYMERIZATION CATALUSYST, IN PROPORTION OF 0.005 TO 0.2 PERCENT BY WEIGHT, E.G., AMMONIUM PERSULFATE. A REDFOX REDUCING AGENT IS PREFERABLE IN THIS SYSTEM.

United States Patent ice Int. on. em 15/40 U.S. Cl. 260-785 R 6 ClaimsABSTRACT OF THE DISCLOSURE The invention provides a process for makingnovel water-soluble polymers which are useful as flocculating agents.These polymers are formed by polymerization of (a) itaconic acid, or thewater soluble sodium or ammonium salts thereof, in proportion of from0.2 to 15 percent by weight; (b) a monomer of an amide of unsaturatedalpha-beta monocarboxylic acid, such as acrylamide or immediatederivatives thereof, in proportion of from to 95 percent by weight; (c)an unsaturated watersoluble monomer, for example: acrylic acid or maleicacid, and the salts of said acids; allylalcohol, and derivativesthereof. The polymerization is carried out by dispersing the threeabove-described monomers (a), (b) and (c) in a water insoluble organicmedium, e.g., toluene in presence of a surface-active agent such assulphonated petroleum distillate with a molecular weight in the range of300 to 1000, a polymerization catalyst, in proportion of 0.005 to 0.2percent by weight, e.g., ammonium persulfate. A Redox reducing agent ispreferable in this system.

BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relatesto new water-soluble substances which are useful as flocculation agents.More particularly, the invention relates to new terpolymer compositionseffective within a great variety of media.

A large number of substances exist that are useful as flocculation orcoagulation agents of solids in aqueous suspension. In the beginning,these substances were of natural origin, such as, for example, starchand aluminum sulphate. Then there appeared synthetic substances usefulas such agents, such as water-soluble polymers. These synthetic polymerscan be divided into three large classifications:

(1) Polymers having negative charges distributed over the polymer chainin an aqueous medium: these are the anionic flocculants;

(2) Polymers having positive charges distributed over the polymer chainin an aqueous medium: these are the cationic flocculants; and

(3) Finally, those polymers which do not form ions in an aqueous medium:these are the non-ionic flocculants.

The polymers of the first categories (1) and (2) are still calledpolyelectrolytes.

These three classes of polymers are obtained in particular byhomo-polymerizing or by co-polymerizing acrylamide with carefully chosenmonomers. Among the anionic flocculants utilized, sodium acrylamide, orammonium acrylate co-polymers have particular importance. It is alsoknown that the flocculation of solids is suitably effected only if thepolymers used are linear polymers, in other words, polymers having theleastpossible ramifications or bridges, and having a molecular weight ofat least However, according to the nature and the concentra tion ofsolids in suspension (the nature of the aqueous medium, its pH, itstemperature, etc.) it is very often difiicult to obtain maximumeflectiveness in the fiocculation. In other words, it is difiicult atthe same time to 3,784,526 Patented Jan. 8, 1974 obtain fiocs havingsufiicient density and dimensions for obtaining a rapid speed ofdecantation and a perfectly clear supernatant liquid.

OBJECTS OF THE INVENTION It is an object of the present invention tofurnish new water-soluble terpolymer compositions utilizable asflocculation agents in a large variety of media, which compositions fallwithin the category of polyanionics.

Another object of the invention is to furnish new fioc culation agents,more specifically, those suitable for improving the speed of decantationof the does by increasing their dimensions and their density.

A further object of the invention is to furnish new flocculation agents,and more specifically, agents which are suitable for improving thelimpidity of the supernatant liquid after decantation of the matter insuspension.

DESCRIPTION OF THE INVENTION The present invention has allowed for thediscovery of new water-soluble polymer substances utilizable asflocculation agents, and more particularly, new water-soluble terpolymersubstances, with high molecular weight, which polymer compositions areadvantageously utilizable as flocculation agents of solids in aqueoussuspension.

The present invention rests essentially on the fact, discoveredunexpectedly, that the polymerization of (a) itaconic acid or itssoluble salts with:

(b) On the one hand, a water-soluble monomer of an amide of anunsaturated a'1pha,beta monocarboxylic acid;

(0) On the other hand, an unsaturated water-soluble monomer having adouble bond in alpha,beta position, results in new terpolymercompositions having excellent solubility in water and advantageouslymeeting the qualities for flocculating agents outlined above.

Thus, it is in the simultaneous co-polymerization of these threesubstances: (a), (b) and (c) in the proportions that are set forthherein and by the methods that are described herein, that the essentialcharacteristic of the present invention is found.

The aforesaid three monomers (a), (b) and (c) are copolymerized in asingle stage, in the presence of some of the others in such manner as toform a terpolymer, the type and the quantity of the recurrent patternsdepending solely upon the quantity of each of the monomers used. It isdifficult to determine the exact structure of the terpolymer, but it isbelieved that a statistical structure can be obtained according to therelative proportions of the different monomers.

It is possible to apply the different techniques of known radicularpolymerization that allow for obtaining the high molecular weights.However, the particular techniques adapted for the obtainment of theterpolymers of this invention are those which are described hereinbelow.

(1) The first essential monomer reagent within the framework of theinvention is itaconic acid or its watersoluble salts of sodium orammonium.

The formula of itaconic acid is the following The quantities of itaconicacid or its water-soluble salts necessary for obtaining the improvementsdescribed within the framework of the invention vary from 0.2 to 15% byweight of the total monomers. A preferred composition of the terpolymercomprises 2 to 10% by weight itaconic acid or its water-soluble salts inrelation to the total (number of) monomers.

(2) The second monomer reagent of the invention is the unsaturatedalpha-beta amide of monocarboxylic acid, having the formula:

R cH,..t :-o-Nrn in which R is hydrogen or an alkyl group.

A preferred second monomer of the inventlon is the acrylamide:

CH =CHCO-NH The quantities of acrylamide can vary in very large limitsfrom 5 to 95% by weight of total monomers, depending on whether onewishes to obtain a terpolymer that is strongly, medium, or slightlyanionic.

(3) The third monomer of the invention is an unsaturated alpha-betaethylene Water-soluble monomer that is co-polymerized with the first twomonomers and contains polar groups. As an example of such monomers,acrylic acid is cited, together with its water-soluble salts;methacrylic acid and its water-soluble salts; the unsaturatedpolycarboxylic acids and their water-soluble salts, such as maleic acid,for example, carboxymethyl acrylate or its salts, the unsaturatedhydroxyl and hydroxy-soluble monomers, such as allylalcohol, ethyleneglycol acrylate or its hydrosoluble salts of sodium and ammonium. The

quantities of this third monomer also vary in somewhat largeproportions, from 5 to 95% by weight of the total monomers content.

The terpolymers according to the invention are obtained by any knownpolymerization techniques that allow for the obtainment of highmolecular weight polymers. However, one particular technique that hasbeen adapted to the obtaining of the terpolymers according to theinvention is the one called inverse emulsion, in the sense that a waterin oil emulsion is prepared from a concentrated aqueous solution of theabove-described monomers in an organic medium, which is neither solventnor monomer nor polymer, and which is obtained by means of asurface-active agent. The aqueous solution of monomers is then dividedinto small droplets dispersed within the organic medium and the radicalpolymerization is begun within these droplets. Thus, the techniqueconsists of effecting a broad polymerization in aqueous solution withinan organic liquid that plays the double role of heat exchanger andfluidizing agent, even though the direct polymerization, without organicmedium, of the aqueous monomer solution would lead to a gel, taking intoaccount the high molecular weight obtained. Another advantage of thistechnique is to be able to obtain at the end of polymerization, directterpolymers in granule or powder form by elimination of thepolymerization water through distillation.

The most important point of this polymerization technique consists ofobtaining, during polymerization, terpolymer microgels dispersed withinthe organic medium which do not bind to each other and which do notstick to the walls of the reactor or to the shaft of the agitator. Theagitation or stirring allows for maintaining the dispersed aqueous phasein the organic phase, but it is necessary to use, in addition, asurface-active agent so as to 0 make maximum avoidance of any stickingof the microgels to the walls and to the shaft of the agitator. Numeroussurface-active agents favoring the water in oil emulsion can be used;however, it has been found that the products best suited to theframework of the invention are deriva- 5 tives of sulphonated petroleumdistillates and their sodium or calcium salts. These petroleum cuts havethe general formula: CXHySO Na or (CxHySOQCa, with x ranging between 20and 30, and y ranging between 30 and 45. The molecular weights of suchsurface-active 7 agents must range between 300 and 1000.

Among the other surface-active agents that can be utilized within theframework of the invention, the esters of sorbitol can be cited, such assorbitol tristearate, the oxyethylene derivates of fatty amines. Thenecessary quan- 75 tities of surface-active agent used within theframework of the invention vary from 0.1 to 2% by weight in relation tothe organic medium.

The aqueous monomer solutions of the invention contain from 30 to byweight of monomers, and from 35 to by weight water. These aqueoussolutions are dispersed within the organic medium by means of agitation,and the surface-active agent is dispersed the proportion of 20 to 30% byweight of aqueous solution to 80 to 70% by weight of the organic medium.A preferred composition is 25% by weight aqueous solution to by weightorganic medium.

By the term organic medium is understood any product which is notsolvent, nor monomer, nor terpolymer which is obtained and which has aboiling point greater than the boiling point of the preferred water. Aproduct allowing for the obtainment of an azeotrope with water ispreferred for facilitating the elimination of the water in the finalphase of the polymerization. Among the numerous products that can beused, aromatic and aliphatic hydrocarbons are cited; a particularlyfavorable product is toluene.

The catalysts used for initiating the polymerization of such a systemare catalysts with radical dissociation, which dissociate under theaction of heat or under the action of a reducer compound at the lowesttemperature. Among the catalysts that are used within the framework ofthe invention, are ammonium persulphate, potassium persulphate,oxygenated water, azo-bis-isobutyronitrate, the organic peroxides andhydroperoxides can be cited.

Among the reducing agents used, sodium metabisulphite, thethiosulphates, the bisulphites, the hydrosulphites are illustrative ofthe invention.

A catalyst system particularly suited to the preparation of theterpolymers according to the invention is a redox system, which allowsfor low temperature polymerization so as to obtain the highest molecularweight. The redox catalyst necessitates a careful elimination of tracesof oxygen dissolved in the medium in order to shorten the treatmentperiod of the polymerization. This is done by carrying out thepolymerization under a current of nitrogen and with slight vacuum so asto eliminate and prevent any entry of air that might be harmful to theobtainment of the high molecular weights. The amounts of catalyst usedvary from about 0.005% to 0.2% by weight in relation to the monomers.The preferred amounts vary from about 0.05% to 0.15% by weight based ontotal monomer content.

The polymerization temperatures according to the invention arepreferably low. They range between 30 and C. These polymerizationtemperatures are obtained by the polymerization heat of the monomers. Itis often necessary to resort to cooling so that the reaction does notbecome violent. An effective means for mastering the polymerizationtemperature is to work under a certain reduced pressure in order tobenefit from the reflux of the organic medium which, when condensing inthe coolant, contributes large calories to the reactional medium. Anadequate polymerization temperature is around 65 to 75 C., underpressure of 200-250 mm. of mercury.

The following examples give some illustrations of the invention but arenot to be construed as limitative of the invention:

EXAMPLE 1 To the foregoing mixture is added 250 g. of acrylamide, whichis dissolved at a temperature of 30 C. In a reactor of 2000 cm. equippedwith an agitator, a thermometer and a direct-reflux coolant, 4 g. of theselected emulsifier (sulphonate of Na from a p roleu cut of PM=450-500)is dissolved in 1500 cm. of tolucue; the solution of monomers preparedabove is added while stirring well so as to disperse correctly theaqueous phase in the toluene and the nitrogen is vigorously purged for15 to 20 minutes.

the reflux and the temperature maintained at 70-72 C. for 45 minutes.After this temperature is obtained, a second quantity of catalyst isadded in order to complete the polymerization and maintained for stillanother hour at 70 C.

Then 0.4 ml. of a ammonium persulphate solu- 5 Afterwards, theazeotropic distillation of the water is tion and 1 ml. of a 10% sodiummetabisulphite solution effected in a separator so as to eliminatearound 220 g. are added and placed in vacuum (250 mm. Hg) while ofwater. In the course of this distillation, the gels present heating thereaction medium in a water bath. Around in the medium are transformedinto white, solid gran- 60-65 C., a thermal reaction is produced. Thetoluene ules. At the end of the distillation of the water, the prodisboiled, the reaction tempered, which is maintained at 10 uct is placedat atmospheric pressure and discharged, 70-75 C. for 30-40 minutes. Thetemperature again while filtering. After crushing and drying, aterpolymer drops to 65-67 C. at the end of this step, a secondquancontaining 5% by weight itaconic acid in Na salt form tity ofcatalyst is added, that is identical to the first, in is obtained; theterpolymer also contains by weight order to complete the polymerization.There is a second F acrylic acid in Na salt form and 80% by weightacrylexothermal reaction, less violent than, the first; the temamide.The viscosity of the terpolymer dissolved at 1% perature rises to 70 C.;this temperature is maintained in water is 3500 (Brookfield RV speed 1).for still another hour; then the water present in the me- The polymerobtained is designated by B in the foldium is vacuum distilled in aDean-Stark trap. The tolulowing tables. ene decants in the upper layerand continually drops EXAMPLE 3 ga the l i gf until afiound Theprocedure is carried out in the same manner as o 0 Tig l d i i t m t iin the previouss examples, but modifying the weight refi a lsgerse t ito uene lationships of the monomers. Thus, a terpolymer is pre- 5.521saszsizasihssisszstrategist; by 22% b we' ht a lic cid and 0 b w rlamide. last traces of water. The product is vacuum dried at 50 25 y 1gcry a 7 y elght ac y 60 C. The reactor contains practically no residuestuck EXAMPLE 4 to the walls.

Finally, a terpolymer powder is obtained that contains P Prepared from.monomers of i we1ght itaconic acld, 15% by welght methacryhc acid 2.5%sodium itaconate, 3.5% sodium acrylate and 94% and 80% by weightacrylamide. It is designated as polyacrylamide, the viscosity of whichat 1% 1n the water ives 2000 c s measured with the Brookfield RV merDmthe followmg Table speed 1 p In order to evaluate the flocculatingproperties of the terpolymers prepared according to the invention, aHydroi i i obtamed 1s deslgnated by A m the followcure apparatus isused; this is a S-beaker unit, each beaker ng a EXAMPLE 2 being of 1liter capacity; the unit is equipped with a variable-speed agitator,driven by a single motor.

10 g. of itaconic acid and 30 g. of acrylic acid are dis- The mediumsubject to flocculation is dispersed by solved in 220 g. of bipermutedwater; by means of a agitation at the rate of 150 r.p.m. Solutions offloccula- 50% sodium solution, the pH is neutralized at 8-8.5. tionproducts are prepared with a concentration of 1% Then 160 g. ofacrylamide is added, while keeping the 40 and increasing quantities ofthese solutions are introduced dissolution temperature less than 30 C.into the beakers. Agitation is eifected for 30 seconds more 1400 cm? oftoluene is placed in the reactor along at 150 r.p.m., then the speed isreduced to 40 r.p.m. The with 5 g. of the selected emulsifier(sulphonate of Na decantation speed is then observed and the limpidityof from a petroleum cut of PM=400 450); the emulsifier is thesupernatant liquid is also noted so as to determine correctly dissolvedin the toluene and with vigorous stirthe necessary quantity forobtaining the best flocculation ring the aqueous mixture of monomers isintroduced. The results. nitrogen is vigorously purged for 20 minutes.The terpolymers described in the previous examples are Then 0.35 ml. ofa 10% ammonium sulphate solution comparable to a commercial copolymer ofsodium is added together with 1 ml. of a 10% sodiummetabisulacrylate-acrylamide (sodium acrylate/acrylamide ratio phitesolution and vacuum heated to 65-70 C. An exoaround 50/50). thermicreaction is produced. The toluene is placed in The results are giveninthe following tables:

TABLE I Results of first medium studied-e kaolin suspension in water at200 p.p.m.

Commercial A B C D polymer Appearance of fiocs- Fatty and thick... Fattyand thick... Fatty and thick Average. Decantatlon speed- 35 sec 35 secsec. Clearness Good- Good. Slightly cloudy; flocs in suspension. Optimumquantity 5 p.p.m 7 p.p.m 7 p.p.m 10 p.p.m 10 p.p.m.

TABLE II Results of second medium studied-a dispersion of titanium oxideat 500 p.p.m.

Competing A B C D product Appearance of docs Fatty and thick..-- Fattyand thlck..... Excellent Excellent Average.

Speed 35s 40 sec. 40 sec sec lminute.

Glearness Excellent Good Excellent Good to excellen Average.

Optimum quantity 5 p.p.m 10 p.p.m 8p.p.m... 7p.p.m 10 p.p.m

TABLE III Results of third mediums studied-a dispersion of champagnechalk at 200 p.p.m

Appearance of flocs Excellent Excellent Excellent...4; ExcellentAverage.

Speed Immediat 10 sec- 8 sec- 15 sec. 0 sec.

Cleamess Excellent Excellent Good to excellent--...- Good Several fleesin suspension.

Optimum quantity 10 p.p.m.--.-. 15 p.p.m 10 p.p.m 15 p.p.m 10 p.p.m.

Among the other mediums studied in which the terpolymers according tothe invention have been utilized successfully, the following are cited:dispersions of iron oxide ore, dispersions of copper ore, uranium, redsludge from the treatment of bauxite, residual industrial water, sewagewater, waste water, carbon dispersions, caustic solutions, lead waterfrom paper mills.

Of course, the invention is not limited to only these applications,rather only to the methods of preparation which have been described byway of example.

What is claimed is:

1. Water-soluble polymer compositions, useful as flocculation agents,which comprise terpolymers from the polymerization of a compositionconsisting essentially of:

(a) a member selected from the group consisting of itaconic acid, andits water-soluble sodium, and ammonium salts, in the proportion of fromabout 0.2 to 15% by weight of total composition;

(b) a monomer of an amide of an unsaturated alpha, beta-monocarboxylicacid, in the proportion of from about to 95% by weight of totalcomposition; and

(c) an alpha, beta-ethylenically unsaturated watersoluble monomer in theproportion of from about 5 to 95% by weight of total composition.

2. Polymer composition according to claim 1, wherein monomer (b) isacrylamide.

3. Polymer composition according to claim 1, wherein monomer (c) is amember selected from the group consisting of acrylic acid, methacrylicacid, maleic acid, and

' water soluble salts of said acids, allyl alcohol, and water solubleethyleneglycol acrylate and salts thereof.

UNITED STATES PATENTS 3,658,772 4/1972 Volk et al. 26080.3 N 3,321,4315/1967 Cruden et al. 26029.6 3,211,708 10/1965 Zimmerman et al. 26078.53,311,579 3/1967 Donat 26023 3,479,283 11/1969 Harrison et al. 210-543,634,366 1/1972 Chujo et al. 26078.5

FOREIGN PATENTS 1,202,929 1/ 1960 France.

JOSEPH L. SCHOFER, Primary Examiner I. KIGHT III, Assistant Examiner US.Cl. X-R.

21054; 26029.6 T, WB

